Update where command to output project paths instead of package paths

The where command was printing OutputPath (the nupkg path) for each
registered project. Changed it to print ProjectPath (the csproj path)
to match the which command's behavior.

https://claude.ai/code/session_01V3PnuN1BXFiVX5aiyXC8hT

Author: claude

src/CommandLine/Commands/Where.cs

@@ -28,7 +28,7 @@ public WhereCommand(XRepoEnvironment environment)
             var packageRegistration = environment.PackageRegistry.GetPackage(name)
                 ?? throw new CommandFailureException(12, $"No package with name '{name}' is registered. Have you ever built it on this machine?");
 
-            Console.Out.WriteList("packages", packageRegistration.Projects.OrderByDescending(p => p.Timestamp).Select(p => p.OutputPath));
+            Console.Out.WriteList("projects", packageRegistration.Projects.OrderByDescending(p => p.Timestamp).Select(p => p.ProjectPath));
         });
     }
 }